I am confused about whether objects when a nonuniform mass density experience net torque during free fall. If you take a rod that is heavier on one end and lighter on the other, should it not experience a net torque and angularly accelerate? But at the same time, the acceleration by gravity is uniform for the whole rod. And usually in the absence of air resistance it wouldn't rotate. It seems it only rotate if there is a pivot point. But I don't understand why.